`progressbar(hide=True)` option for hiding the progress bar

[simonw]

Often when I use the Click progressbar I find myself wanting to conditionally hide it. Sometimes it's because there's another option in play which means I have output to display in place of it - others it's because I added a --silent option (as seen in curl) for disabling it entirely.

It's actually a bit tricky doing this at the moment, due to its use as a context manager.

What I'd really like to be able to do is this:

hide = True  # or False depending on various things

with click.progressbar(items, show_eta=True, hide=hide):
    for item in items:
        process_item(item)

[simonw]

Here's one workaround I've used for this, which feels pretty messy:

class NullProgressBar:
    def __init__(self, *args):
        self.args = args

    def __iter__(self):
        yield from self.args[0]

    def update(self, value):
        pass


@contextlib.contextmanager
def progressbar(*args, **kwargs):
    silent = kwargs.pop("silent")
    if silent:
        yield NullProgressBar(*args)
    else:
        with click.progressbar(*args, **kwargs) as bar:
            yield bar

Then:

        with progressbar(
            length=self.count, silent=not show_progress, label="1: Evaluating"
        ) as bar:

[simonw]

It looks like there's already a property that could be used for this:

click/src/click/_termui_impl.py

Line 107 in ca5e1c3

self.is_hidden: bool = not isatty(self.file)

So the implementation may be as straight-forward as adding a hide: bool = False parameter and then doing this:

 self.is_hidden: bool = not hide and not isatty(self.file) 

[simonw]

I tried this:

        with click.progressbar(
            ids, label="Calculating similarities", show_percent=True
        ) as bar:
            if hide:
                bar.is_hidden = True

But it still shows the bar once at the start of the loop, because of this:

click/src/click/_termui_impl.py

Lines 110 to 113 in ca5e1c3

	def __enter__(self) -> ProgressBar[V]:
	self.entered = True
	self.render_progress()
	return self

Which calls render_progress() before I've had a chance to toggle is_hidden to False:

click/src/click/_termui_impl.py

Lines 231 to 239 in ca5e1c3

	def render_progress(self) -> None:
	import shutil
	if self.is_hidden:
	# Only output the label as it changes if the output is not a
	# TTY. Use file=stderr if you expect to be piping stdout.
	if self._last_line != self.label:
	self._last_line = self.label
	echo(self.label, file=self.file, color=self.color)

[davidism]

I'm wary of changing our progress bar at this point. I generally recommend that people use tqdm or rich if they need features beyond what ours provides. Both of them have a way to hide a progress bar.

In this case, it does seem relatively straightforward to modify our existing hide behavior with a parameter, so I think I'm ok with this.